1. Technical Field
The disclosure is related generally to turbine system. More particularly, the disclosure is related to a steam turbine system and a steam turbine control system for the steam turbine system.
2. Related Art
Conventional steam turbine systems are frequently utilized to generate power for electric generators. More specifically, a working fluid, such as steam, is conventionally forced across sets of steam turbine blades, which are coupled to the rotor of the steam turbine system. The force of the working fluid on the blades causes those blades (and the coupled body of the rotor) to rotate. In many cases, the rotor body is coupled to the drive shaft of a dynamoelectric machine such as an electric generator. In this sense, initiating rotation of the steam turbine system rotor can initiate rotation of the drive shaft in the electric generator, and cause that generator to generate an electrical current (associated with power output).
The amount of power generated by the steam turbine during operation, and ultimately the efficiency of the steam turbine, oftentimes stated in the form of ‘heat rate’, may be dependent upon a plurality of factors. For example, one such factor may include the efficiency of the condenser of the steam turbine system. The condenser may be responsible for receiving exhaust steam that has flowed through the various sections (e.g., high-pressure section, low-pressure section) of the steam turbine system, and converting the exhaust steam to fluid. The fluid may be subsequently converted back to steam and flowed through the various sections of the steam turbine system again. When exhaust steam enters the condenser at an undesirable temperature (e.g., higher than optimum conversion temperature), a portion of the exhaust steam may be removed from or rejected by the condenser in order for the condenser to convert all of the exhaust steam to fluid. The overall efficiency of the steam turbine system may be reduced when a portion of the exhaust steam is rejected by the condenser. To compensate for this loss in efficiency, larger condensers are used in the steam turbine system, such that less exhaust steam having an undesirable temperature may be rejected. However, a larger condenser requires an increased power requirement for operation, and also increases the size of the steam turbine system.
An additional factor that may affect the efficiency of the steam turbine system is the temperature of the fluid prior to reaching the boiler of the steam turbine system. That is, the overall efficiency of the steam turbine system may be directly affected by the temperature of the fluid just prior to the fluid reaching the boiler and subsequently being converted to operational steam. The greater the difference between the actual fluid temperature and a desired conversion temperature, the greater the power requirement for the boiler to convert the fluid to steam. That is, as the difference between the actual fluid temperature and the desired conversion temperature increases, the power required to convert the fluid to steam also increases, increasing the heat rate of the steam turbine system. The power required by the boiler to convert the fluid to steam may be generated from other portions of the steam turbine system, which may result in a decrease in power generated by the steam turbine system, and ultimately may decrease the efficiency of the steam turbine system.